Robb made a promise that he would never force her to marry, yet, Sansa knew that she can't always escape her duty. She already resigned to the fate of having another loveless political union with one of Robb's governors or advisors. Then came Jon. Based on the valar-morekinks prompt: "Star-crossed lovers in the Ottoman Empire. Sansa as the young widowed sister of Robb the Ottoman Sultan, and Jon as his best friend/advisor/servant who was kidnapped from a foreign land and sold into slavery as a boy."